Unless you're reloading 37 caliber or larger rifles with 300 grain or heavier bullets, or, loading ammo that'll be fired in full auto machine guns that might jam or the ammo get banged around enough in transport and push the bullets deeper into the case, crimping case mouths onto bullets ain't needed.
Standard reloading dies for rifles make case necks plenty tight enough to hold bullets very well in place. No crimping's needed.
And if you do feel a need to crimp case mouths into bullets, that'll degrade accuracy 'cause it adds another variable to the equasion; bigger spreads in case neck tension. And it unbalances bullets that don't have a crimping groove (cannelure) around them like most military rifle and most pistol bullets have. I don't know of anyone reloading .30-06 ammo that has to crimp their bullets in place, but lots of people feel they need to; there is a difference. Well, maybe someone with a 5-pound .30-06 using a long chamber throat shooting 250-gr. bullets with max loads. The military arsenals quit crimping .30-06 match ammo case mouths on match bullets with cannelures back in the 1930's for use in M1903 Springfields 'cause it was more accurate without crimping. Along comes the Garand and that ammo didn't have any problems in semiauto fire from 8-round clips.
Yes, there is a better (very accurate) way to test a seated bullet grip by the case neck. How tight a bullets gripped is typically referred to in the ammo making industry as how much force is needed to push (or pull) the bullet out of the case. Use a collet type bullet puller put in a board that's clamped to a benchtop such that it's off the edge. Wire a bucket to a shell holder, put a round in the puller, slide the shell holder onto the case rim then start filling the bucket with bullets. When the case finally gets pulled off the bullet, weigh the bucket and its contents. About 25 pounds is good for .30-06 home reloads. You may get by with a bit less.
Proof test loaded ammo by filling the rifle's box magazine with them and a round in the chamber then fire that round. Check the rounds in the magazine to see if any bullets have been pushed deeper in their cases from recoil. If none are, reload another round from the magazine, shoot it then check the rounds in the magazine then repeat this for all the loaded rounds. If the last round in the magazine doesn't have its bullet set back your neck tension (release force) is good. If not, then you can polish down the expander ball in your full length sizing die (or use a smaller bushing in your bushing die) and try again.
Last edited by Bart B.; December 2, 2012 at 08:35 AM.